add the dart:__interceptors library to the dart sdk (flutter#13125)

Author: devoncarew

sky/packages/sky_engine/BUILD.gn

@@ -4,6 +4,7 @@
 
 import("//build/fuchsia/sdk.gni")
 import("//third_party/dart/sdk/lib/_http/http_sources.gni")
+import("//third_party/dart/sdk/lib/_internal/js_runtime/interceptors_sources.gni")
 import("//third_party/dart/sdk/lib/async/async_sources.gni")
 import("//third_party/dart/sdk/lib/collection/collection_sources.gni")
 import("//third_party/dart/sdk/lib/convert/convert_sources.gni")
@@ -84,6 +85,14 @@ copy("_http") {
   ]
 }
 
+copy("_interceptors") {
+  lib_path = rebase_path("_internal/js_runtime", "", dart_sdk_lib_path)
+  sources = rebase_path(interceptors_sdk_sources, "", lib_path)
+  outputs = [
+    "$root_gen_dir/dart-pkg/sky_engine/lib/_interceptors/{{source_file_part}}",
+  ]
+}
+
 copy("internal") {
   lib_path = rebase_path("internal", "", dart_sdk_lib_path)
   sources = rebase_path(internal_sdk_sources, "", lib_path)
@@ -175,6 +184,7 @@ copy("copy_dart_ui") {
 group("copy_dart_sdk") {
   deps = [
     ":_http",
+    ":_interceptors",
     ":async",
     ":collection",
     ":convert",

sky/packages/sky_engine/lib/_embedder.yaml

@@ -15,9 +15,10 @@ embedded_libs:
   "dart:ui": "ui/ui.dart"
   "dart:wasm": "wasm/wasm.dart"
 
-  # The internal library is needed as some implementations bleed into the
+  "dart:_http": "_http/http.dart"
+  "dart:_interceptors": "_interceptors/interceptors.dart"
+  # The _internal library is needed as some implementations bleed into the
   # public API, e.g. List being Iterable by virtue of implementing
   # EfficientLengthIterable. Not including this library yields analysis errors.
   "dart:_internal": "internal/internal.dart"
-  "dart:_http": "_http/http.dart"
   "dart:nativewrappers": "_empty.dart"